Model engine fuel



Patented Mar. 30, 1954 "John W. Brodhacker',

Terre Haute, Ind., assignor to Commercial Solventss Corporation, Terre Haute,-'Ind.; a corporation of Maryland No .-Draw ing.; Application February 3,1950, Serial No. 142,356

11 Claims- .(Cl. id-53) This invention relates to fuels 'for internal combustion engines of the, high speed type such as model engines for midget racing cars, modelairplanes, etc.,

to improve the ignition characteristics.

Fuels generally used in the .type of engines contemplated here. are .nitroparafiin-methanol and more, ,pa1'ticularly it relates to '1gnlt1on promoters,..added" to such fuels-in order in reality a semi-compression;

chamber as an ignition charge where thefuel-ai'r 1 mixture is then spontaneously ignited by a combination .of compression, heat, and catalytic action from the walls of 'the'combustion chambar and from a glow plug whichis generally a platinum wire electrically heated for startingi,

and then heated by thecombustion of the engine after-the engine ,has ..been.-started.

The nitroparaflins suitable for use in nitroparaffin-methanol basefuels are the lower mononitrpparaffins including nitromethane, unitro-i X ethane, lenitropropanaland 2enitropropane. ,Of these I; prefer to use nitromethane since. there are successive lossesuin powerdeveloped by the fuel as the numberof carbonatoms'in nitropareflin n r ases-W Nitromethane-methanol mixtures, while conceded to be better than any otherfuel for model engines, have several disadvantages when the object of model engines-is considered, 'For-instance in dealing with model airplanes, the object is for the engine to develop maximum power so that the highest speeds possible can be obtained. This is realized through the development of the absolute maximum number of pro peller revolutions per minute. In order for this object to be obtained, the fuel used must be completely and almost instantaneously ignited for if it is not ignited almost at once there is a lag in combustion and the maximum number of propeller R. P. M. cannot be reached. Such a difiiculty leads to the other defect in that the fuel is not completely ignited resulting in carbon formation and exhaust of fuel with consequent waste. While nitromethane-methanol mixtures have been found to have very high ignition rates as well as being almost completely consumed still there is some lag in ignition and some lack of complete ignition.

The object of the present invention is to provide a lower mononitroparaffin-methanolbase fuel for model engines of the type described which has an increased rate of ignition and the property of complete combustion upon ignition thus giving an increase in power delivered through an increased number of propeller revolutions per minute in the case of model-airplane engines.

I have discovered that by adding 2,2-dinitropropane to the mononitroparaffin-methanol fuel mixtures, I can improveothe ignition rate and the completeness .of ignition of the fuel with a consequent increase in power delivered as evidenced by an increase in the number of propeller revolutions per minute in the case of model airplane engines.

,The amount of 2,2-dinitropropane to be added to the fuel mixture dependson theproportion of the components of the fuel. Generally," the amount .to be used may be said to range from 0.25% to 2.0% by weight of thefinal'mixture with the best results usually being obtained when 1% is used.

It should be pointed out that most fuels used in model engines must contain a lubricant, castor oil usually .being'used for that purpose. The amount of castor oil to be used depends on the engine design, and generally, if it is'to be used at all,..the amount employed ranges from 15% to 30% by volume of the final mixture. I prefer to use castor oil in the amount of 25% by volume of the final mixture.

The lower mononitroparaflin, generally nitromethane, and the methanol are. ordinarily blended in proportions which deliver the'most power for the particular engine being used. Generally it can be said that the amount of nitroparamn an be as high as 45% of the final mixture when nitromethane is used, however, I prefer to use fuels containing from 30 to 40% nitromethane by volume. When nitroethane or nitropropane are used, the amount to be blended with the methanol is successively decreased.

The eflectiveness of 2,2-dinitropropane can be demonstrated by reference to tests run with model engines where fuels with and without the ignition promoter were used and the number of propeller revolutions per minute measured.

The following tables show the results of tests run with various fuels, the compositions of which are indicated. All percentages in the following tables and in the attached claims are by volume except that percentages of 2,2-dinitropropane are by weight.

TABLE I M 00021 49 engine Fuel Formula R. P. M

37.5% Nitromethane 37.5% Methanol 10, 500 25% Castor Oil 32.2? ls itzgmetlhane .5 1 e ano 25% oastor on 2% 2,2-Dinitropropan g; llzalitzgmetlhane.

e ano 25% castor on 1% 2,2-Dinitr0propane TABLE II Dooling 60 engine Fuel Formula R. P. M

TABLE III Dooling 60 engine Fuel Formula I R. P. M.

30% Nitromethaue. 43% Methanol. 25% Castor Oil 2% 2,2-Diuitropropanc 4 ueuureS or formulae shown therein, all obvious equivalents being considered within the scope of my invention as disclosed in the specification and attached claims.

Now having disclosed my invention, what I claim is:

1. A fuel containing a base consisting of methanol and a mononitroparafiine containing from one to three carbon atoms per molecule, the said fuel further containing 2,2-dinitropropane in an amount sufficient to act as an ignition promoter.

2. A mononitromethane-methanol base fuel containing 2,2-clinitropropane in an amount sufficient to act as an ignition promoter.

3. A fuel containing a base consisting of methanol and a mononitroparaffin containing from one to three carbon atoms per molecule, the said fuel further containing from 0.25% to 2.0% 2,2- dinitropropane.

4. A mononitromethane-methanol base fuel containing from 0.25% to 2.0% 2,2-dinitropropane.

5. A mononitroethane-methanol base fuel containing from 0.25% to 2.0% 2,2-dinitropropane.

6. A mononitropropane-methano1 base fuel containing from 0.25% to 2.0% 2,2-dinitropropane.

7. A mononitromethane-methanol base fuel containing 1% 2,2-dinitropropane.

8. A model engine fuel which comprises from 10% to 94% methanol, 5% to 45% mononitromethane, 15% to 30% castor oil, and 0.25% to 2.0% 2,2-dinitropropane.

9. A model engine fuel which comprises from 35% to 45% methanol, 30% to 40% mononitromethane, 15% to 30% castor oil, 0.25% to 2.0% 2,2-dinitropropane.

10. A model engine fuel which comprises 37.5% mononitromethane, 36.5% methanol, 25% castor oil, and 1.0% 2,2-dinitropropane.

11. A model engine fuel which comprises 30% mononitromethane, 43% methanol, 25% castor oil, and 2% 2,2-dinitropropane.

JOHN W. BRODHACKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,495,094 Morgan May 20, 1924 1,572,750 Morgan Feb. 9, 1926 2,387,403 McCracken Oct. 23, 1945 2,433,943 Zwicky Jan. 6. 1948 2,584,803 Hannum Feb. 5, 1952 OTHER REFERENCES Klein: Fuels for Jets" in S. A. E. Journal, December 1947, pps. 22-28. 

1. A FUEL CONTAINING A BASE CONSISTING OF METHANOL AND A MONONITROPARAFFINE CONTAINING FROM ONE TO THREE CARBON ATOMS PER MOLECULE, THE SAID FUEL FURTHER CONTAINING 2,2-DINITROPROPANE IN AN AMOUNT SUFFICIENT TO ACT AS AN IGNITION PROMOTER. 